Some 40 million people are living with HIV/AIDS, >50% higher than 1991 projections by the WHO. Young people and women account for about 50% of those currently infected and projections point to an additional 45 million people worldwide by 2010. Although anti-viral drug combination therapies have succeeded in decreasing virus replication, long term survival is uncertain and therapy is not readily available to the majority. The opportunity to avert or change the course of HIV-1 infection and subsequent development of AIDS exists. The discovery of new agents that block the replication of HIV-1 in infected individuals has contributed to our ability to slow the course of disease. The design of effective vaccines and drugs is evolving rapidly. However, a detailed understanding of the HIV-1 virus and how it interacts with the human immune system is essential. A critical component of this effort is the training of young investigators to be well-versed in both basic and clinical sciences, who will dedicate themselves to these objectives long-term. Our mission is to train basic and clinical scientists capable of conducting independent high-quality AIDS research using the diverse disciplines of immunology, cell biology and virology. Long-term scientific training programs are critical to this effort to limit the consequences of HIV-1 infection and curtail the epidemic through prophylaxis of HIV-1 transmission. These primary considerations led to the development of this training program in 1990. The program is directed by Harvey Cantor and supported by a renowned group of faculty mentors, comprised of leading investigators in diverse fields. Through its affiliation with the Harvard Medical School, the Training Program is further enhanced by its affiliation with the HMS CFAR and the Dana-Farber/Harvard Cancer Center. In this application, we describe the progress and achievements of this program during its tenure and outline objectives for its continuation over the next five years.